The program of this Center for the investigation of occupational pulmonary disease continues to be primarily involved with the characterization of disorders of structure and function of the lungs and their relation to the occupational environment. Clinical, epidemiologic, radiographic and physiologic methods are used in the qualitative and quantitative measurement of any adverse biological effects relating to the lungs and airways of workers. A major interest of the Center is to help in the establishment of those methods of measuring pulmonary function which are most useful as an epidemiologic tool. Characterization of the environment is based on air sampling data leading to specific identification of adverse pollutants for each job to include longitudinal estmates and, finally, providing dose-time relationships for the exposure being studied.